{"id":5379,"date":"2015-10-26T12:57:12","date_gmt":"2015-10-26T04:57:12","guid":{"rendered":"http:\/\/rmohan.com\/?p=5379"},"modified":"2015-10-26T12:57:25","modified_gmt":"2015-10-26T04:57:25","slug":"ip-address-with-ifconfig-and-sed","status":"publish","type":"post","link":"https:\/\/mohan.sg\/?p=5379","title":{"rendered":"IP address with ifconfig and sed"},"content":{"rendered":"

Well, my new favorite approach is to pipe ifconfig<\/code> into a single sed<\/code> command \ud83d\ude42<\/p>\n

ifconfig | sed -n -e ‘s\/:127\\.0\\.0\\.1 \/\/g’ -e ‘s\/ *inet addr:\\([0-9.]\\+\\).*\/\\1\/gp’<\/div>\n

 <\/p>\n

So, how does it work? Well, there are two filters (aka scripts, ie the parameters after the -e<\/code> flags). The first one, s\/:127\\.0\\.0\\.1 \/\/g'<\/code>, simply strips out all occurrences of the local loopback address (127.0.0.1) – this can be left out if you want to include the loopback address in the results. And the second filter, 's\/ *inet addr:\\([0-9.]\\+\\).*\/\\1\/gp'<\/code> matches all lines with IP addresses, strips all but the IP address itself, and prints the matching line (note the ‘p<\/code>‘ at the end of the filter, which works in with the -n<\/code>flag at the stared of the sed<\/code> command).<\/p>\n

Obviously that explanation is only meant to be a brief summary. You should consult the sed<\/code> manual is you’re still unsure of how \/ why this works… or post a question below \ud83d\ude42<\/p>\n

Just for comparison, here’s some examples of how others do the same thing:<\/p>\n